Lens curvature variation apparatus

Abstract

The present invention relates to a lens curvature variation apparatus. The lens curvature variation apparatus according to an embodiment is a lens curvature variation apparatus for varying a curvature of a liquid lens which is variable based on an applied electrical signal. The lens curvature variation apparatus includes a lens driver to apply the electrical signal to the liquid lens, a sensor unit to sense the curvature of the liquid lens formed based on the electrical signal, and a controller to control the lens driver to form a target curvature of the liquid lens based on the sensed curvature, wherein the lens driver supplies the electrical signal to the liquid lens according to a switching operation of a switching element, and includes a detection element connected to one end of the switching element, wherein the sensor unit senses an electrical signal detected by the detection element. Thereby, the curvature of the lens can be sensed quickly and accurately.

The invention claimed is: 
     
       1. A lens curvature variation apparatus for varying a curvature of a liquid lens that is variable based on an applied first electrical signal, the lens curvature variation apparatus comprising:
 a lens driver to apply the first electrical signal to the liquid lens; 
 a sensor unit to sense the curvature of the liquid lens formed based on the first electrical signal; and 
 a controller to control the lens driver to form a target curvature of the liquid lens based on the sensed curvature, 
 wherein the lens driver supplies the first electrical signal to the liquid lens according to a switching operation of a switching element, and comprises a detection element connected to one end of the switching element, 
 wherein the sensor unit senses a second electrical signal detected by the detection element, and 
 wherein the controller comprises:
 an equalizer to calculate a curvature error based on the calculated curvature and the target curvature; and 
 a pulse width variation controller to generate and output the pulse width variation signal based on the calculated curvature error. 
 
 
     
     
       2. A lens curvature variation apparatus for varying a curvature of a liquid lens that is variable based on an applied first electrical signal, the lens curvature variation apparatus comprising:
 a lens driver to apply the first electrical signal to the liquid lens; 
 a sensor unit to sense the curvature of the liquid lens formed based on the first electrical signal; and 
 a controller to control the lens driver to form a target curvature of the liquid lens based on the sensed curvature, 
 wherein the lens driver supplies the first electrical signal to the liquid lens according to a switching operation of a switching element, and comprises a detection element connected to one end of the switching element, 
 wherein the sensor unit senses a second electrical signal detected by the detection element, 
 wherein the lens driver comprises:
 a first upper switching element and a first lower switching element connected in series to each other; and 
 a second upper switching element and a second lower switching element connected in parallel to the first upper and lower switching elements and connected in series to each other, and 
 
 wherein the detection element is connected between a ground terminal and one of the first lower switching element and the second lower switching element. 
 
     
     
       3. The lens curvature variation apparatus according to  claim 1 , wherein the sensor unit senses an area of a boundary region between an insulator on an electrode and an electroconductive aqueous solution in the liquid lens or a change in the area based on the second electrical signal detected by the detection element. 
     
     
       4. A lens curvature variation apparatus for varying a curvature of a liquid lens that is variable based on an applied first electrical signal, the lens curvature variation apparatus comprising:
 a lens driver to apply the first electrical signal to the liquid lens; 
 a sensor unit to sense the curvature of the liquid lens formed based on the first electrical signal; and 
 a controller to control the lens driver to form a target curvature of the liquid lens based on the sensed curvature, 
 wherein the lens driver supplies the first electrical signal to the liquid lens according to a switching operation of a switching element, and comprises a detection element connected to one end of the switching element, 
 wherein the sensor unit senses a second electrical signal detected by the detection element, 
 wherein the liquid lens comprises:
 a common electrode; 
 a plurality of electrodes spaced apart from the common electrode; and 
 a liquid and an electroconductive aqueous solution, the liquid and the electroconductive aqueous solution being disposed between the common electrode and the plurality of electrodes, and 
 
 wherein the sensor unit senses the second electrical signal detected by the detection element while a level of a pulse applied to the common electrode or a first electrode of the plurality of electrodes is varied. 
 
     
     
       5. The lens curvature variation apparatus according to  claim 4 , wherein the sensor unit comprises:
 an integrator to sum levels of the second electrical signal detected by the detection element while the level of the pulse applied to the common electrode or the first electrode of the plurality of electrodes is varied; and 
 an amplifier to amplify the second electrical signal summed by the integrator. 
 
     
     
       6. The lens curvature variation apparatus according to  claim 5 , wherein a sum value of the levels of the second electrical signal obtained while the level of the pulse applied to the common electrode or the first electrode of the plurality of electrodes is varied is varied depending on an area of a boundary region between an insulator on the electrodes and the electroconductive aqueous solution in the liquid lens or a change in the area. 
     
     
       7. The lens curvature variation apparatus according to  claim 5 , wherein an output value of the integrator increases as a time difference between a first pulse applied to the common electrode and a second pulse applied to the first electrode among the plurality of electrodes increases. 
     
     
       8. The lens curvature variation apparatus according to  claim 4 , wherein the sensor unit comprises:
 a zero-crossing detector to detect zero-crossing of the second electrical signal detected by the detection element while the level of the pulse applied to the common electrode or the first electrode of the plurality of electrodes is varied. 
 
     
     
       9. The lens curvature variation apparatus according to  claim 8 , comprising:
 a first converter to convert an output value of the zero-crossing detector into a digital signal, 
 wherein the output value of the converter increases as a time difference between a first pulse applied to the common electrode and a second pulse applied to the first electrode among the plurality of electrodes increases. 
 
     
     
       10. The lens curvature variation apparatus according to  claim 1 , comprising:
 a second converter to convert an output signal output from the sensor unit into a digital signal. 
 
     
     
       11. The lens curvature variation apparatus according to  claim 5 , wherein the curvature of the liquid lens increases as an area of a boundary region between an insulator on the electrodes and the electroconductive aqueous solution in the liquid lens or a change in the area increases. 
     
     
       12. The lens curvature variation apparatus according to  claim 4 , wherein, when different voltages are applied to a first electrode and a second electrode among the plurality of electrodes, a first capacitance of a first end portion of the liquid is different from a second capacitance of a second end portion of the liquid. 
     
     
       13. The lens curvature variation apparatus according to  claim 4 , wherein the curvature of the liquid lens increases as a time difference between a first pulse applied to the common electrode and a second pulse applied to one of the plurality of electrodes increases. 
     
     
       14. The lens curvature variation apparatus according to  claim 4 , wherein, while a pulse is applied to the common electrode and at least one of the plurality of electrodes, the controller calculates the curvature of the liquid lens based on a capacitance sensed by the sensor unit, and outputs a pulse width variation signal to the lens driver based on the calculated curvature and the target curvature,
 wherein, when the calculated curvature is less than the target curvature, the controller controls a duty of the pulse width variation signal to increase. 
 
     
     
       15. The lens curvature variation apparatus according to  claim 14 , wherein the controller comprises:
 an equalizer to calculate a curvature error based on the calculated curvature and the target curvature; and 
 a pulse width variation controller to generate and output the pulse width variation signal based on the calculated curvature error.